Abstract

Room temperature electronic diffusion is studied in thick epitaxial GaAs lift-off films using a novel circularly polarized photoluminescence microscope. The method is equivalent to using a standard optical microscope and provides a contactless means to measure both the charge and spin diffusion lengths simultaneously. The measured values of and are in excellent agreement with the spatially averaged polarization and a sharp reduction in these two quantities ( from 21.3 to and from 1.3 to ) is found with increasing surface recombination velocity. Outward diffusion results in a factor of 10 increase in the polarization at the excitation spot. The range of materials to which the technique can be applied, as well as a comparison with other existing methods for the measurement of spin diffusion, is discussed.

Received 13 July 2010Accepted 03 September 2010Published online 21 October 2010

Acknowledgments:

The authors acknowledge T. Verdier and T. Porteboeuf for their help in setting up the circularly polarized optical microscope, J.-F. Lampin for fruitful discussions, and X. Wallart for the epitaxial growth. This work was partially funded by the ANR (Grant No. SPINJECT-06-BLAN-0253).